I set an background image but i can't actually see it all
In 2.79 background images have settings in the Properties shelf on the right of the 3d viewport. There is Opacity slider which by default is set to 0,5 (50%). Set it to higher value if you want the image to become less transparent.



See more about how to setup background images while in 2.79 How do I set a background image while I am editing?

Note that in 2.8 background images are used in another way